Design and manufacturing of racing cars pose high levels of requirements, constrains and limitations that typically contradict each other. For example, the cars chassis must be rigid to stand high energy impacts and yet be light weight so as to impose as low as possible burden to the cars motor. The cars chassis need to be light weight also for reasons of dynamic stability. In addition, the cars center of gravity needs to be as low as possible and as centered as possible for dynamic stability considerations, yet the heaviest elements—the engine and the driver—may not be located very low for obvious reasons.
One very limiting constraint applied with respect to racing cars of the class Formula 1000 is the need to use motors of 1000 cc manufactured for motorcycles. A definition of the binding design constrains regarding racing cars of the Formula 1000 category may be found, for example, in the General Competition Rules (GCR) document that is issued by the Sports Car Club of America Inc. (SCCA) (see in: http://cdn.growasseets.net/user_files/scca/downloads/000/013/696/GCR-_Updated_April_2016.pdf?1459462401). In the 2016 edition, the following definition is found: “Engines: A. Motorcycle-based 4-cycle up to 1000 cc” (GCR of 2016 edition, pp. 368). Further binding rules define the very limited number of changes that may be applied to such engines.
This means that the power block, i.e., the motor itself and its gearbox, which, in the case of a motorcycle, are made as a unified unit, need to be embedded in a racing car chassis and provide torque to the cars wheels while the motorcycle's power block is typically designed to provide torque via a chain and sprockets and, therefore, has its sprocket's axis protruding out of the power block sideways with respect to the longitudinal axis of the motorcycle that is aligned with the travel direction. This poses great trouble to the designers and manufacturers of a Formula 1000 racing cars, since the natural entry point to a differential gearbox (DGB) used for powering the wheels is designed to connect to a shaft aligned with the longitudinal center line of the car, not as the case is with a power block of a motorcycle.
The typical solution for this problem is powering the DGB from the side, and not from the front of the gearbox, using a pair of sprockets and a chain. This power transmission line imposes several disadvantages such as weighty transmission, the need to mechanically maintain the chain frequently, an early beginning of loss of power due to chain/sprocket wear, limitation on the power/speed ratio of the sprocket-to-sprocket transmission when high transmission ratio is required due to a use of a too little section of the smaller sprocket, etc. However, turning the power block 90 degrees about a vertical axis was never an option, as it would have caused several design difficulties. One main difficulty stems from the fact that, when the motor cycle's power block is turned 90 degrees about a vertical axis to turn its power output axis facing backwards, this axis is located too far to the side from the longitudinal line passing through the entry point to the DGB, which causes the drive shaft connecting the output of the power block to the input of DGB to be positioned in a too large angle relative to the line aligned with the axes of these output and input points. While certain bearing assemblies may support such large angles for a power transmission shaft, the price of power loses (excessive friction and heat loses) is too high to be acceptable in a racing car.
The traditional positioning of the motorcycle's power block, as described above, imposes additional disadvantages. One is the need to locate the power block far enough behind the driver's seat in order to leave enough place for the exhaust pipes leaving the motor's head in the forward direction and need to be turned sideways or backwards. The resulting location of the power block to the back of the car is for itself a disadvantage regarding the car's dynamic stability and road behavior.